Эсминцы типа Zumwalt (USS DD-21/USS DD(X)/DDG-1000)

To evaluate the relative effectiveness of conventionally and
nuclear-powered aircraft carriers in meeting national security
requirements and objectives, GAO identified three principal measures of
effectiveness: (1) overseas presence, (2) crisis response, and
(3) war-fighting.
Using the Navy’s Force Presence Model and data, GAO’s analysis shows
that, on a relative basis, a force of 12 conventional carriers, when
compared to a force of 12 nuclear carriers, can provide a greater level of
overseas presence in the European Command, the Central Command, and
the Western Pacific1 or that a force of 11 conventionally powered carriers
can provide an equivalent level of forward presence as a force of 12
nuclear-powered carriers. Because a conventionally powered carrier’s
maintenance requirements are not as stringent and complex as those of a
nuclear-powered aircraft carrier, the conventionally powered carrier
spends a smaller proportion of its time in maintenance than does the
nuclear aircraft carrier and, thus, is more available for deployment and
other fleet operations. Unified Commanders consider the quality of
presence of the two types of carriers to be the same.
Navy carriers have been tasked to respond to various crises across the full
range of military operations, from humanitarian assistance to major
theater wars. Nuclear-powered carriers are known for their abilities to
sustain long duration high-speed transits. Although both types of carriers
can transit to crisis areas at the same top speed, the conventional carriers
take somewhat longer to cover long distances than nuclear carriers due to
their need to refuel. For example, GAO’s analysis of Navy data indicates
that in an 18-day voyage from the U.S. West Coast to the Persian Gulf, a
distance of about 12,000 nautical miles, steaming at a sustained speed of
28 knots, a conventional carrier would arrive about 6 hours later than a
nuclear carrier. On a shorter voyage from the U.S. East Coast to the
eastern Mediterranean Sea, a distance of about 4,800 nautical miles, a
conventional carrier would arrive about 2 hours later than a nuclear
carrier. Neither of these two examples include the time delay caused by
refueling the other ships in the battle group, which would have the same
refueling requirements, regardless of the carrier’s propulsion.
Conventionally powered carriers can be available sooner for large scale
crises because it is easier to accelerate or compress their maintenance.
Carrier maintenance periods can be shortened by varying degrees,
depending on the stage of the maintenance being performed.2 The degree a
depot maintenance period can be shortened—or surged—depends on
when the decision is made to deploy the carrier. For both types of carriers,
the decision must be made early if the period is to be substantially
shortened. Due to the complexity of its maintenance, a nuclear carrier’s
maintenance period cannot be surged to the same degree as that of a
conventional carrier. In addition, the crews for both carrier types train to
the same standards, except for the power-plant crew, and spend
comparable time in predeployment training.
GAO found little difference in the operational effectiveness of nuclear and
conventional carriers in the Persian Gulf War. Although the Navy had
opportunities to place more nuclear carriers in the combat zone, it
followed previously planned deployment schedules. As a result, five of the
six carriers that participated in the air campaign were conventionally
powered. GAO found that the Navy operated and supported all six carriers
and their battle groups in essentially the same manner during the conflict.
Each battle group was assigned its own dedicated support ships, which
enabled frequent replenishment of fuel and ordnance. Conventional
carriers replenished aviation fuel about every 2.7 to 3.1 days and the
nuclear carrier every 3.3 days—after only a fraction of their fuel and
supplies were exhausted. The distance to targets and the number and mix
of aircraft aboard each carrier, rather than propulsion type, determined
the number of air sorties flown. The average number of sorties flown were
nearly identical for both types of carriers when based on the number of
aircraft assigned to the respective carriers.
In comparing their characteristics and capabilities, GAO found that the two
types of carriers are similar in many respects. For example, both carriers
follow the same operational guidance; have the same standard airwing;
and, can surge to conduct additional air operations, if necessary. The most
noticeable differences are the nuclear carrier’s ability to steam almost
indefinitely without needing to replenish its propulsion fuel and its larger
aircraft fuel and ordnance storage capacity, thereby further reducing
dependence on logistics support ships. The larger storage capacity is
primarily due to design decisions that have little to do with propulsion
type.3 Nuclear carriers still need periodic resupply of aviation fuel,
ordnance, and other supplies, and as such, remain dependent on logistics
support ships to sustain extended operations at sea. Logistics support
ships are an integral part of carrier battle groups and accompany the
groups during peacetime deployments, in crisis response, and during
wartime. Nuclear carriers also can accelerate faster than conventional
carriers, enabling them to respond faster if conditions affecting the
recovery of landing aircraft suddenly change, but the Navy could not
provide any examples where an aircraft was lost because a conventionally
powered carrier could not accelerate in sufficient time.